Hell: temporary punishment?

In the wake of the controversy over Love Wins, someone recently suggested to me that perhaps hell is not eternal after all and that those sent there might one day complete their sentences, much as a prisoner serves for a certain period and is then released. It’s an intriguing and hopeful thought, but it raises two difficulties, as I see it.

First, my understanding, following that of the historic church, is that Jesus Christ paid the penalty for sin for all those who are in Christ. Mere human beings could never pay the price for their own transgressions. To suggest that they could  by, in effect, serving time  would seem to imply that there is a second path to salvation other than through the only begotten Son of God. But, as the Heidelberg Catechism puts it, “no mere creature can bear the weight of God’s eternal anger against sin” (Q&A, 14), and “Only those are saved who by true faith are grafted into Christ and accept all his blessings” (Q&A, 20).

Second, would not a non-eternal, temporary hell be tantamount to purgatory? Article XXII of the Thirty-Nine Articles of Religion definitively condemns belief in purgatory, but if one conceives of the possibility of completing one’s sentence in hell, then it seems to me that the distinction between purgatory and hell fades away.